Welding method

ABSTRACT

A method of resistance welding electrically conductive bodies together wherein projection means and sealing means are positioned between overlapped portions of such bodies, the bodies then being subjected to pressure and current to seal and weld the bodies together.

United States Patent [72] Inventor Freeman M. Vowels Louisville, Ky.

[21] Appl. No. 757,169

[22] Filed Sept. 3, 1968 [45] Patented May 4, 1971 [73] AssigneeAmerican Air Filter Company, Inc.

Louisville, Ky.

[54] WELDING METHOD 4 Claims, 1 Drawing Fig.

U.S. Cl 219/92 823k 11/10 Field of Search 219/92- [56] References CitedUNITED STATES PATENTS 1,039,135 9/1912 Johnson 219/94 2,452,805 1 l/l948Sussenbach 219/92X 2,902,589 9/1950 Wirta 2 l 9/92X 3,067,488 12/ 1962Bennett et a1 2l9/93X Primary Examiner-4. V. Truhe Assistant Examiner-J.G. Smith Attorney-Ralph B, Brick ABSTRACT: A method of resistancewelding electrically conductive bodies together wherein projection meansand sealing means are positioned between overlapped portions of suchbodies, the bodies then being subjected to pressure and current to sealand weld the bodies together.

PATENIEn 1m 4m v 3576,5363

INVENTOR. Five/nan M. Vane/s 634, 4 6. dime 1 WELDING METHOD BACKGROUNDOF THE INVENTION The present invention relates to a method of resistancewelding and more particularly to a method of resistance welding by spotbinding lapped metallic sheets.

The present invention recognizes that it has been known in one area ofthe art of electrically welding metallic parts together to limit theweld to restricted portions or so-called spots by providing embossmentson the metallic parts to be welded or by providing separate pelletsbetween the parts so that the current and pressures employed in thewelding operations are localized by the formations and the parts weldedtogether at the area enclosing the formations. in addition, the presentinvention recognizes that it has been known in another area of the artof electrically welding metallic parts together to apply a sealingcompound between lapped metal bodies to be spot-welded together so as toeffect a tight, permanent seal.

SUMMARY OF THE INVENTION The present invention, recognizes thesignificant advantages in each of these several known methods of weldingwhich are from distinct areas of the welding art, combines the varioussteps of such several methods to provide a new, useful, and unobviousmethod of welding which is straightforward, economical, and efficient inits execution, permitting both the welding an sealing together of twooverlapped metallic bodies in the same process with a minimum of steps,a minimum of effort, and a minimum of materials. In addition, thepresent invention can be used with metallic bodies of various thickness,avoiding the need for displacement and distortion of the metallic bodieswhich are to be joined.

Various other features of the present invention will become obvious toone skilled in the art upon reading the disclosures set forthhereinafter.

More particularly, the present invention provides a method of resistancewelding electrically conductive metallic bodies together comprising thesteps of: positioning in overlapping spaced relationship the inneradjacent surfaces of metallic bodies to be joined; placing strip meansof electrically conductive sealing composition between the overlappinginner adjacent surfaces; positioning electrically conductive metallicprojection means on the sealing strip means to provide at least onecontact resistance point on the strip; moving the inner adjacentsurfaces of the metallic bodies into electrically conductive contactwith the strip of sealing composition and metallic projection means;causing an electrical current to flow through the contact resistancepoint to concentrate the heating effect to locally fuse the metallicbodies and melt the sealing strips therearound;and applying pressure toforce the molten metal to fonn a weld and themelted plastic compound toform a seal between the metallic bodies.

It is to be understood that various changes can be made in the severalsteps of the method described hereinafter without departing from thescope or spirit of the present invention.

Referring to the drawing, FIG. 1 discloses an exploded view showing twoplates about to be welded in accordance with one advantageous embodimentof the present invention.

As can be seen in the drawing, metal plates 2 and 3 are shown in spacedoverlapped relation. Positioned between these two plates in facedopposed relation are strips of sealing material 4 and 6. The sealingmaterial utilized can be any one of several types known in the art. itis desirable that material be in the plastic stage to supporttherebetween in firm prepositioned spaced relationship projectionpellets 7. Pellets 7 can be ferrous balls, and are carefully selected insize in accordance with the thickness and other geometric parameters ofplates 2 and 3. Advantageously, sealing tape such as that sold bySandon, Inc., PO. Box 120, 12 Bennett Drive, Granville, N.Y. under thename Weldseal" can be utilized. This tape is a soft, permanently plasticproduct, manufactured in a film of fixed thickness and width forapplication between the members to be welded prior to the welding steps.The tape forms a tight gasket the entire length of the seam and flowsout only enough to form a smooth bead along the exposed edges of theseam. Upon cooling, the tape returns to its original plasticcharacteristic. The uniformity of materials and performance insures theretention or exclusion of moisture. Advantageously, the tape can beprovided with a pressure-sensitive adhesive. This adhesive permits afirm positioning of the pellets 7 on the tape and enhances the overalloperation. It also is to be understood that other sealing compositiontapes can be utilized. For example, sealing tapes such as disclosed inexpired US. Pat. Nos. 2,452,805 and 2,510,727, issued to P. Sussenbachand assigned to the Presstite Engineering Company, St. Louis, Mo., canbe utilized.

ln carrying out the operation, pellets 7 are placed in preselectedspaced relationship between sealing tapes 4 and 6 so as to be sandwichedtherebetween, the adhesive on the sealing tapes insuring that pellets 7are held in a firm, preselected position. This assembly of tapes andpellets is then placed between overlapping inner adjacent surfaces ofmetallic bodies 2 and 3 to be welded together. With the various partsheld firmly in proper position, welding electrodes 9 are then appliedalong the seam under the usual pressure. The pressure of electrodes 9forces the plates toward one another and squeezes tapes 4 and 6 andpellets 7 therebetween. Upon application of pressure and passage of thewelding current through the electrodes, the plates, the pellets, and thesealing composition, the plates become welded together at spaced pellets7 along the seam, pellets 7 melting along with strips 4 and 6therearound. The applied pressure and the heat generated by the weldingcurrent causes the molten metal of pellets 7 to form the weld and themelted plastic compound of strips 4 and 6 the seal between the metallicbodies 2 and 3. Upon cooling, the composition of strips 4 and 6 returnsto the plastic condition to seal the seam along its entire length withthe welds hardening in the form of spot welds at the points ofprojection.

lclaim:

l. A method of resistance welding two electrically conductive metallicbodies together comprising the steps of: positioning in overlappingspaced relationship the inner adjacent surfaces of said metallic bodiesto be joined; placing strip means of electrically conductive sealingcomposition between said overlapping inner adjacent surfaces;positioning electrically conductive metallic projection means in theform of separate pellets on said sealing strip means to provide at leastone contact resistance point on said strip; moving said inner adjacentsurfaces of said metallic bodies into electrically conductive contactwith said strip of sealing composition and metallic projection means;causing an electrical current to flow through said contact resistancepoint to concentrate the heating effect to locally and substantiallymelt said pellets and fuse the metallic bodies and melt the sealingstrips therearound; and applying pressure to force the molten metal toform a weld and the melted plastic compound to form a seal between themetallic bodies.

2. The method of claim 1 wherein said electrically conductive metallicpellet projection means is comprised of a plurality of spaced ferrousball members of a diameter preselected in accordance with the dimensionof the metallic bodies to be welded.

3. The method of claim 1 wherein said sealing strip is of thermoplasticmaterial and includes an adhesive for said electrically conductivemetallic projection means.

4. The method of claim 1, wherein said strip means comprises a pair ofopposed electrically conductive strips, said metallic projection meansbeing positioned between said strip means.

1. A method of resistance welding two electrically conductive metallicbodies together comprising the steps of: positioning in overlappingspaced relationship the inner adjacent surfaces of said metallic bodiesto be joined; placing strip means of electrically conductive sealingcomposition between said overlapping inner adjacent surfaces;positioning electrically conductive metallic projection means in theform of separate pellets on said sealing strip means to provide at leastone contact resistance point on said strip; moving said inner adjacentsurfaces of said metallic bodies into electrically conductive contactwith said strip of sealing composition and metallic projection means;causing an electrical current to flow through said contact resistancepoint to concentrate the heating effect to locally and substantiallymelt said pellets and fuse the metallic bodies and melt the sealingstrips therearound; and applying prEssure to force the molten metal toform a weld and the melted plastic compound to form a seal between themetallic bodies.
 2. The method of claim 1 wherein said electricallyconductive metallic pellet projection means is comprised of a pluralityof spaced ferrous ball members of a diameter preselected in accordancewith the dimension of the metallic bodies to be welded.
 3. The method ofclaim 1 wherein said sealing strip is of thermoplastic material andincludes an adhesive for said electrically conductive metallicprojection means.
 4. The method of claim 1, wherein said strip meanscomprises a pair of opposed electrically conductive strips, saidmetallic projection means being positioned between said strip means.